A quantum dot (QD) embedded in a circuit quantum electrodynamics (cQED) architecture offers a promising platform for both quantum information processing and the study of fundamental light-matter interactions, as well as enabling analog quantum simulations. Recent experiments have demonstrated strong coupling in semiconducting QD-cavity hybrid devices, where resonator microwave photons interact with the charge or spin degrees of freedom in QDs via their electric dipolar interaction.
A particularly compelling direction for future research is achieving ultrastrong coupling between superconducting cavity photons and QD electrons, which could be realized by increasing resonator impedance, enhancing electric field fluctuations, and optimizing gate lever arms.
Our research focuses on double quantum dots (DQDs) defined in planar Germanium and crystal-phase-defined DQDs within InAs nanowires. The strong spin-orbit interaction (SOI) in these semiconductor materials simplifies spin qubit design, enabling rapid spin manipulation through electrical signals and eliminating the need for micromagnets.
Building on these properties, strong coupling between microwave photons and charge qubits in planar Ge, as well as charge and singlet-triplet qubits in InAs nanowires, has recently been demonstrated. These advancements pave the way for significant progress in quantum technologies, making this an exciting and impactful field of research.
The postdoctoral project focuses on two main goals:
These goals will be pursued by:
Achieving ultrastrong coupling will establish a distinctive platform for exploring fundamental quantum phenomena and advancing quantum technology applications. Success in this project could unlock new research directions at the intersection of semiconductor and superconducting quantum technologies. The long-term aim is to integrate these platforms coherently, significantly broadening the scope of solid-state quantum hardware and introducing innovative strategies for quantum information technology.
The successful candidate will work on integrating QD devices defined in planar Ge heterostructures and crystal-phase-defined DQDs within InAs nanowires with superconducting high-impedance resonators. Device fabrication, including manipulation and transfer of nanowires, will take place in the Center of Micro-Nanotechnology (CMi) cleanroom at EPFL, which is fully equipped with advanced tools for nanofabrication. High-quality semiconductor materials will be provided through collaborations with our project partners at Lund University and the University of Basel. The hybrid structures will be tested in a dilution refrigerator at 10 mK, using both cryogenic and room-temperature microwave electronics. The candidate will perform low-noise cryogenic and high-frequency measurements to characterize the coupling of charge and spin states in artificial atoms with the high-impedance environment. Success in this role will leverage our in-house expertise in nanofabrication, state-of-the-art microwave measurements, and the collaborative network within our research group.
Responsibilities may include:
We are seeking candidates with a strong interest in quantum technology based on semiconducting/superconducting quantum circuits. Proficiency in English, in reading, writing and discussing scientific material is essential, along with strong teamwork and excellent communication skills.